1. Field of the Invention
The present invention relates to a rare earth magnet having high electric resistance.
2. Description of the Related Art
Low-priced ferrite magnets have been conventionally used in many cases as magnets for permanent magnet motors. However, with downsizing and increases in the performance of rotating electrical machines, consumption of high-performance rare earth magnets is increasing year by year. Typical rare earth magnets include Sm—Co type magnets and Nd—Fe—B type magnets, and developments for achieving higher performance and lower prices are now in progress.
However, since the rare earth magnet is a metallic magnet, the rare earth magnet has low electric resistance. For this reason, eddy current loss is increased when the rare earth magnet is incorporated in a motor, thereby degrading motor efficiency. Accordingly, various techniques have been proposed to solve such a problem by means of enhancing the electric resistance of the rare earth magnet itself.
Japanese Patent Application Laid-Open No. 10-321427 discloses a rare earth magnet having a structure in which rare earth magnet particles are bonded to SiO2 and/or Al2O3 particles. Presence of SiO2 and/or Al2O3 between the rare earth magnet particles can enhance the electric resistance of the rare earth magnet.